Fluid control valves are used in a variety of environments to open and close a valve port, often under high pressure conditions. One example of a high pressure valve seal is shown for instance in U.S. Pat. No. 2,621,011 issued to T. R. Smith on Dec. 9, 1952. In this patent, a resilient sealing element or ring is provided with a resilient sealing, rounded lip for sealing contact with a flat seating surface on a valve plunger. The valve plunger compresses the resilient sealing member a predetermined amount in order to obtain a reliable seal of the fluid passing through the valve.
In many applications, rather than a resilient sealing contact between a metal member and a resilient or elastomeric sealing member, it is required to provide a metal to metal sealing contact, particularly in extremely high pressure environments were resilient members cannot be used effectively. One example of such high pressure valve sealing requirements is in fuel injection systems, such as electronically-controlled fuel injectors and pressure control valves therefor.
An example of an electrically-controlled fuel injector is shown in U.S. Pat. No. 4,392,612 issued to Deckard, et al. on Jul. 12, 1983. In Deckard, et al. the injector includes a mechanically-actuated fuel pumping plunger and an electrically-actuated fuel pressure control valve assembly. The pressure control valve assembly includes a solenoid-operated poppet valve that controls fuel pressure in the unit injector in order to control fuel injection delivery. Fuel pressure is controllably enabled to be developed within the injector by electrical actuation of the pressure control valve assembly. Fuel pressure is controllably prevented from developing within the injector by not electrically actuating the pressure control valve assembly.
In such electronically-controlled unit injectors, the armature of the pressure control valve assembly moves the metal poppet valve in one direction until it engages a metal valve seat and holds the poppet valve in the fuel sealing position to enable fuel pressure to be developed in the unit injector, eventually resulting in fuel injection. At the end of the fuel injection cycle, the solenoid is electrically deenergized and a return spring backs the poppet valve off of the valve seat and returns the poppet valve to the valve open position which prevents the development of fuel pressure by spilling the fuel back to the fuel reservoir.
Typically, such pressure or spill control valve assemblies use complimentary angled annular seating surfaces on the metal poppet valve and the metal valve seat to achieve the sealing engagement therebetween so as to shut off the fuel.
Several problems have been noted in these presently available pressure control valve assemblies and it is desired to seek solutions thereto. As an example, the sealing engagement of the normally provided angled surfaces between the metal poppet valve and the metal seat requires a given pressure which in turn requires that the electrical solenoid coil and the input electrical energy be sufficient to supply the given pressure. Such angled seat configuration also requires a given valve opening force in order to cause the poppet to move so as to thereby disengage the angled surface on the valve member from the angled surface on the valve seat.
If the poppet valve could be made to seat with less than the presently required electromagnetic force, the solenoid coil could be made smaller and require less electrical input energy. Similarly, on the valve opening cycle, if the required opening force on the poppet valve could be reduced, then the poppet valve would move more quickly in disengagement from the valve seat which would cause a sharper end of fuel injection. A sharper end of fuel injection is desired so as to provide higher engine thermal efficiency and lower exhaust emissions.
Also, because of the high pressure fluid conditions, it is desired to use non-resilient member to non-resilient member sealing rather than non-resilient member to resilient member sealing to avoid leakage problems encountered with using resilient seals in such high pressure fluid conditions.
It is therefore desired to provide a fluid valve for use in high pressure conditions which will overcome one or more of the problems as set forth above.